No one can "Reply" to emails (GMail) after update

Hello, all! I'm stumped: Unlike many, seemingly, the update performed on my Z10 went well, as time-consuming as it was. What seems to have happened, however, is no one can now "Reply" to any of my email sent from my primary account, a GMail account. Although I haven't made any changes to my email settings prior to the update, I've checked what settings I may, and can find nothing amiss. Any thoughts, suggestions, ideas, would be greatly appreciated. Thank you for your time.

I wonder if I may be jumped the gun, here. Still conducting tests, and it seems like select users are not working, so I'm seriously starting to lean toward configuration issues on their end. A number of tests to my own separate accounts have been successful.

Yes, thanks, that works; as have other tests to separate accounts. I suspect the problem lies with select individuals who are claiming to have issues replying to me.
Thank you for your considerate reply.